In the field of the computer graphics, three-dimensional space representation is an increasingly felt problem. The multi-block approach for grid generation assumes that the computational domain is divided into a finite number of subdomains, called blocks, each one topologically equivalent to a cube, i.e. it is formed of six faces, twelve edges and eight corners. These blocks are also defined as hexahedral blocks. The computational grid is therefore created in every block obtaining a final multi-block grid which covers the whole computational domain.
It is known to handle such three-dimensional space representation with CAD systems such as CATIA of Dassault Systemes. With these systems is possible to ideally divide the three-dimensional space into a number of hexahedral blocks by defining the surfaces which delimite such blocks. What is obtained is a plurality of four-sided finite surfaces defined by three-dimensional Cartesian coordinates.
The next step is to define the topology of the three-dimensional domain, i.e. to create a correlation among the surfaces in order to make the system recognize which surfaces form an hexahedral block.
None of the known systems is able to do this topology definition and a user should define each block by manually indicating the six surfaces "belonging" to that block. This is a very time consuming process which heavily affect the performance of the system.